When sputtering 2-dimensional surfaces, for instance for fabricating displays (e.g. TFT displays) or electronic devices, typically multiple layers are deposited, at least some of them comprising different materials.
In order to obtain this, in prior art solutions the substrate is physically moved from one sputter chamber where one or more layers of a first material are deposited onto the substrate, to another sputter chamber where one or more layers of a different material are sputtered onto the same substrate.
Within one sputter chamber the substrate is typically being held substantially static during sputtering, although this is not required. The substantially static configuration has the advantage that fewer contaminating or defect generating particles are introduced in the coating, but it requires a plurality of targets or a large single target for which the two dimensional size of the sputter device holding these plurality of targets or this large single target is similar to or larger than the two dimensional size of the substrate. Contaminating or defect generating particles in the sputtered coating generate defects in the structure of the sputtered coating and are therefore to be avoided. It is known that moving the substrate while sputtering increases the concentration of contaminating particles in the substrate. Typically the size of the contaminating particles is between 10 and 30 μm.
An issue occurring in cluster coaters for sputtering large area surfaces is the uniformity of the resulting coating. Typically the spread in thickness of the coating over the area of the substrate is around 10% or even more of the thickness of the coating.
In view of the above requirements there is still room for improvements in sputtering systems for sputtering large area surfaces.